From: SonOfLilit <sonoflilit@...>
Date: 2007-07-15T17:52:03+09:00
Subject: Re: xkcd and ugly code

Here's a bit of DRYing up of your code, which isn't a good idea - as
David mentioned, there are better ways to do this. Note: untested.

menu= [2.15, 2.75, 3.35, 3.55, 4.20, 5.80]
target= 15.05

def r(state, menu, target) # state is an array of indexes. returns nil
unless a solution was found
  i = state.length
  if i < menu.length
    0.upto(target/menu[i].to_i) do |a|
      state.shift(a)
      retval = r(state, menu, target)
      state.unshift
      return retval if retval
    end
  else
    total = (0..i-1).inject{0) {|index, m| m += state[index]*menu[i - index]
    if (total - target).abs<0.01 then
      return state
    end
    return nil
  end
end

total = 0.0
# this line is twisted, but I really enjoyed writing it. so it stays.
this isn't production code anyway. and you'll have to implement
collect_with_index, I think.

print r([], menu, target).
  collect_with_index{|amount, i| total += amount*menu[i]; "#{amount} *
$#{menu[i]}" }.
  push("------ #{total}").join("\n")